1. Field of the Invention
The invention relates to a process for melting oxidic slags and combustion residues having a minimum content of metallized portions such as, e.g., iron and/or carbon carriers, of 3% by weight.
2. Prior Art
Melting aggregates in which solid charges are to be melted under defined conditions in the first place have become known in connection with scrap melting. It was the aim of such processes to produce a molten steel melt from scrap and/or metal-containing wastelike substances, wherein the process was controlled in a manner that, in addition to a slag melt, a metal bath was formed by reduction of the melt. As a rule, acidic slag control was chosen and pig iron having a relatively low carbon content was melted, which, however, involved the relatively expensive purification of the offgases forming. Thus, a process for continuously melting scrap iron sponges or the like in a shaft furnace has already become known, for instance, from DE 25 04 889 A1, wherein a flame produced by fuel-oxygen-burning was to act on the charging material column in countercurrent from below. With such a process control, a reducing zone was produced below the oxidizing meltdown zone by admixing large coal pieces of low activity to the charging material. Such melting processes usually were aimed at melting steel or pig iron, to which end reducing conditions were necessary.
For the subsequent further treatment of slags with a view to purifying said slags in order to recover valuable raw materials and/or additives suitable for the production of cement, it has already been proposed to effect melting under oxidizing conditions. Thus, for melting inorganic combustion residues optionally loaded with heavy metals and/or heavy metal compounds, it was proposed, for instance, in AT 401 301 to feed gaseous oxygen or fuels to the charge and treat the same in a reactor while realizing as complete an oxidative reaction as possible under the formation of a foamed slag.